Thermo-electric couple.



No. 885,430. PATENTED APB.. 2l, 1908.

. W. H. BRISTOL.

THERMO ELECTRIC COUPLE. APPLICATION FILED DBO. 27, 1907.

WILLIAM H. BRISTOL, OF NEW YORK, n. Y.

, THERMO-ELECTRIC COUPLE.

nasca-13o.

Specification of Letters Patent.

' Patented Aprn 21, 190,8.

Application filed December 27, 1907. Serial No. 408,316.

ycouples and' generators; and it has for its object a thermo-electric couple whose elements .are .capable of lwithstanding extremely-high .temperatures and which do notappreciably alloy with most molten metals.

In the accompanying drawings-Figure 1 shows a thermo-electric couple inserted into a section of a furnace. Figs-2 to 5 show various forms of thermo-electric couples.

It is well known that thermo electric vcouples consisting of the platinum-rhodium p elements, or of elements of the baser metals `ticu arly gold and silver.'

cannot be used forthe measurement of temperatures above 3000O Fahr. and are practically useless for the purpose of measuring the tem eratures of baths of molten metals, par'- In the use of such couples in baths of molten metals, it has been found that they readily alloy with the same, thereby aecting the purity of the bath as well as deteriorating or destroying the couple cylinder 10 as one ofthe elements, and an 1nitself.

It is the object of my invention to devise a couple having elements`such as will resist ytemperatures considerably above 3000o Fahr.; and elements such as will not alloy appreciably with most 'molten metals.

have found that a substantial thermoelectric eiect may be produced by employing as the two lelements of a thermo-electric couple, dierent forms, kinds or grades of carbon or graphite. A. couple composed of the so-called Acheson' graphite, an artificial and extremely ur'e product, and a rod of the natural grap lte made up with some suitable binding material gives a very satisfactory thermo-electric indication. I have lalso found that a thermo-electric effect may be'produced fromthe same kind of carbon or graphite by varying the same as in density, or byaltering the kind, naturey or quantity of the binding material employed, or by an intermixture of various impurities, such as for example-sodium silicate, ,barium chlorid, etc. Couples may be made having onel element of the pure carbon or graphite, and the.

Vmetalit'self forms the connection between therewith. These elements form 'thermothat the thermo-electric effects element 11 of the natura other of the same or diHerent carbon or gra hite varied as above described.

arious kinds of clays may serve, and I havev found 15% to 20% of Bavarian clay,

which is practically free from iron, to be par- 53 ticularly satisfactory in this respect.

In using a couple of this character, the two elements 10 and 11 are preferably in the form of hollow cylinders or rods. In Fig. 1 the couple is shown in the form of a long rod passing through a section of the furnace 12, the two elements form one continuous rod being molded together at the hot end or junction 13 which is located at a portion of the. furnace, the temperature of which it is desired to measure. Figs. 2 to 4 show the elements 10 inthe form of a rod and the element 11 inthe formV of a hollow cylinder surrounding the same. In Fig. 2 the two elements are shown separated by the insulating material 18 and are pointed as shown, the same being ada ted to be dipped into baths ofmolten meta such as the bath 19, Fig. 5, which figure also shows a couple with separated elements.l In both cases, the molten the two elements, `as fully set forth in my prior U. S. Patent $764,176' of July 5, 1904. l v

Fig. 3 shows a couple'composed of an outer ner rod 11 screwed into same, or as shown in Fig. 4 sim ly molded thereto and forming the hot en or junction 13.

Owing to the high thermal conductivity of the carbon or graphite employed, as well as to save in the amount of this material, prefer to compound the couple by utilizing other and cheaper elements 14 and 15 in connection electric connections 16 and 17 between the carbon or graphite rods, the elements being selected of such material and so arranged roduced at said connections neutralize eac fully set forth in my prior U. S. patent., #764,177 of July 5, v1904.

In the case of the element 10 being of the Acheson or`artificial graphite, and the proximately 5% of nickel and 95% of iron; 110

other, as

graphite as pre- '105 and to theelement 11, the element 14 of cop-V per! v By employing a cou le of the character herein set forth, both o whose elements are 'capable of resisting eXtreme' tem' eratures and both of which do not apprecia ly alloy with Vmost molten metals, I obtain an inex- `pensive couple for measuring temperatures l taining some impurity, such that a substantial thermo electric effect lis produced by heating the junction of the two elements.`

I claim 1. A thermo-electric couple, the two elements which consist of graphite.

2. A thermo-*electric couple, Vone element of which consists of substantially purecarbon, and the other of carbon containing van impurity.

3. A thermo-electric couple, one element of which consists of substantially of pure graphite, and the otheregraphite containing animlpurity'. l 4.- thermo-electric couple, the two ele- :ments of which consist of carbon, and one of `1 the elements containing a cl'ay.

5. A thermo-electric'couple, the two ele- 7. A thermo-electric couple, the two elements of whichconsist of carbon, Aand oneof the elements containing Bavarian clay.

8. A thermo-'electric couple, the two elements of which consist of graphite, and one of the elements containing abinding material.

9. A thermo-electric couple, the two elements of which consist of gra hite, and each containing a binding'material).

10. A thermo-electric couple, the two elements of whichconsist of gra hite, and one of the elementsy containing a c ay.

11. A thermo-'electric' couple, the two elements of which consist of graphite, and each containing a different clay.

12. A thermo-electric couple, the two elementsof which consist of graphite, and one of the elements containing a clay substantially freroin iron.

13. A thermo-electric couple, the two elements of which consist of graphite, and one i of the elements containin Bavarian clay.

.Signed/at New York, in the county of New York and State of New York this 26th day of December A. D. 1907.

WILLIAM H. BRISTOL.

Witnesses:

FREDK. F. SCHUETZ, SALLY O. YUDIZBY. 

